Dual lubricating system for airplane engines



y 1932- R. L. MEREDITH 1,358,638

DUAL LUBRICATING SYSTEM FOR AIRPMWIE ENGINES Filed April 18. 1928 i all! I Russel. .4. L. MEREO/ 771' atentecl May 17, 1932 UNITED STATES PATENT. OFFICE DUAL LUBRICATING SYSTEM FOR AIRPLANE ENGINES Application filed April 18, 1928. Serial No. 270,948.

This invention relates to internal combustion engines, but more particularly to aeronautical and other engines of the dry sump type requiring heavy lubricating oil of high 5 viscosity. a

d In internal combustion engines, the lubrieating oil thickens under the influence of low temperature. In the case of aeronautical and like motors, this condition gives rise m to difficulties in starting and may result in serious injury and damage to the engines. To overcome these disadvantages, it is common practice to heat the lubricating oil in cold weather to facilitate starting and to assist the flow of oil to the moving parts 1m- 'mediately thereafter. Such practice, however, is extremely inconvenient, and does not fully meet the requirements, as injury may result from friction before the heated Oll g can flow through the system to the moving parts of the engine. I

The object of this invention is to correct these conditions, to the end that such engines may be readily started in cold weathenand as the moving parts of the engine are sufficiently lubricated at starting and immediately thereafter to insure proper and safe operation and without danger of injury and damage to the engines.

"With this object in view the invention consists of the novel lubricating s stem and in the novel arrangement of in ricating Oll tank, as will be first fully described and afterwards specifically pointed out in the appended claims.

Referring to the accompanying drawing The figure is a diagrammatic view of the lubricating system illustrating the lubricat ing oil tanks and their connections.

Referring to the drawing by reference numerals 1 indicates the main oil tank for the heavy oil required for normal eration of the engine. 2 indicates the oil eed line to the engine (not shown) and 3 indicates the return oil line from the engine to the main tank.

Disposed within the main tank 1, is a supplemental oil tank 4 to receive a light oil of low viscosity. 5 indicates an oil feed line ill to from said supplemental tank to a two-way valve 6 located in the oil feed line 2, while 7 indicates a return oil line from a two-way valve 8 in the return oil line 3.

The foregoing description and the accompanying drawing disclose one embodiment'of the invention, its operation being as follows: When employing this system in an air-- plane, and the plane being in normal flight, the two-way valves are set to permit the heavy lubricating oil in the main tank 1 to pass to and from the engine. Just prior to landing, however, the link 9 connecting the two twoway valves is moved so as to shut oif the supply and return of heavy oil from and to the main tank 1, and to open the feed and return lines 5 and 7 of the supplemental tank to and from the engine. This operation starts a flow of light oil from the supplemental oil. tank 4 to the oiling system of the engine, which is continued for a period of time suflicient to insure a film of said light oil throughout all of the moving parts of the engine. WVhen the engine is stopped there remains on all of the moving parts of the engine a-film of lubricating oil of low viscosity. Upon cranking the engine again after the same has been allowed to become co1d,'-the pistons and other moving parts of the engine are free to move unrestricted by the high viscosity of heavy lubricating oil normally used. The engine is warmed up with the same setting of the two two-way valves as when the engine was stopped, and as the circulation and heating of the lubricating oil is rapid, the light oil in the supplemental tank 4 quickly becomes heated. As said tank 4 is disposed within the main tank 1 and immersed Within the heavy oil therein, said heavy oil is thereby heated to increase its fluidity. The link connecting thetwo-way valves is then moved to throw the latter into position of shutting off the supply of oil from the supplemental tank 4 and to cut the main tank 1 into communication with the oiling system of the engine and supply the same with the usual heavy oil for sustained normal operation of the engine. Naturally, there will-be a dilution of each oil supply by the amount of the other contained in the engine itself. But in a dry sump aeronautical engine to which this 100 itself much more oil than a whirlwind motor.

19 No exact dimensions are given since they will vary for each type of engine, and the system is generally applicable to all aeronautical engines of the dry sump type.

The advantages of this arrangement of lu- .bricating oil tanks will be at on obvious to those skllled inthe art without further discussion or description, and having fullydescribed the. invention, I do not wish to be understood as limiting myself to the exact construction herein set forth, as the same is susceptible to changes in the construction and arrangements of the parts withoutdeparting from the spirit and scope of this invention, and I consider myself clearly entitled to all 95 such changes and modifications as fall within the limit and scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A device of the character described including a main lubricating oil tank, a feed line from the tank to an engine, a return line from the engine to the tank, a supplemental lubricating oil tank within the main tank, a feed line from the supplemental tank to supply oil therefrom to the engine, a return line to the tank to receive oil from the engine, a two-way valve in the feed lines from the tanks, a two-way valve in the return lines to the tanks, and means connecting said valves for simultaneous actuation.

2. A device of the character described including a main lubricating oil tank, a feed line from the tank to an engine, a return line from the engine to the tank, a supplemental lubricating oil tank within the main oil tank, a feed line from the supplemental tank to the feed line of the main tank to supply oil therefrom to the engine, a return line to the supplemental tank from the return line of the main tank to receiveoil from the engine, and valves in the saidlines to cut the tanks into communication with the engine selectively.

3. A device of the character described inv eluding a main tank, a feed line from the tank, a return line to the tank, a supplemental tank within the main tank, a feed line from the supplemental tank, a return line to the supplemental tank, and means for shutting off the feed and return lines of one tank and simultaneously opening the corresponding lines of the other tank.

4. A device of the character described including a main tank, a feed line therefrom,

a return line thereto, a supplemental tank within the main tank to heat the contents of the main tank, a feed line therefrom and a return line thereto, and means for feeding from either tank selectively, said means including a single control valve for each pair of feed lines and return lines respectively.

5. A device of the character described, including a main supply source of heavy lubricating oil, a feed line from the main supply source to an engine, a return line from the engine to said main supply source, a supplemental supply source of light lubricating oil in close relation to saidmain supply source in such manner asto be in heat interchanging relation thereto and" means for cutting in the feed from and cutting out the return to either supply source selectively.

6. A dual-lubrication system for an airplane engine comprising a main supply source of oil of suitable viscosity for use in the normal operation of the engine, a supplemental supply source of oil of low viscosity in heat interchanging relation to the said main source for use-when starting and warming the engine in cold weather, and

means for placing the said main and supplemental supply sources into and out of communication separately and alternatelywith the engine for supplying the latter during idle periods with the oil of low viscosity and during operative periods with the oil of suitable viscosity.

7. A dual lubrication system for an airplane engine comprising an outer container for oil of a viscositysuitable for operation of the engine, an inner container for oil of' low viscosity in heat interchanging relation to the contents of the outer container, and means for placing said containers separably and alternately into and out of communication with the engine.

8. A dual lubrication system for an airplane engine comprising an outer container 4 for oil of a viscosity suitable for operation of the engine, an inner container for oil of a low viscosity in heat interchanging relation to the contents of the outer container, a feed and return line common to both-containers, and means for placingthe said containers separately and alternately into and out of ppmmunication with the said feed and return In testimony whereof-I atlix my signature.

vRUSSELL L. MEREDITH. 

